April 1975

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Features

The Proliferation of Nuclear Weapons

Unless the major nuclear powers begin to live up to their obligations under the Nonproliferation Treaty, it seems likely that a large number of near-nuclear countries will emulate India and join the "nuclear club"

By William Epstein

Experiments in the Visual Perception of Texture

The discovery of textures that are indistinguishable even though their constituent elements are different suggests how the visual system organizes patterns into the percepts "figure" and "ground"

By Bela Julesz

Cyanate and Sickle-Cell Disease

The abnormal hemoglobin of people who suffer from sickle-cell anemia is made to behave like normal hemoglobin in experiments with the administration of the simple chemical sodium cyanate

By Charles M. Peterson and Anthony Cerami

Dinosaur Renaissance

The dinosaurs were not obsolescent reptiles but were a novel group of "warm-blooded" animals. And the birds are their descendants

By Robert T. Bakker

The Walls of Growing Plant Cells

They consist of cellulose fibers bound together by molecules made of many sugar units. The structure of those molecules is now known well enough to account for some of the properties of the cell wall

By Peter Albersheim

Giant Clams

The tridacnids, related to cockles, include the largest bivalve in evolutionary history. Their size is probably due to the fact that photosynthetic algae live in their tissues and nourish them

By C. M. Yonge

The Rotation of the Sun

The sun turns once every 27 days, but some parts turn faster than others. Such variations are clues to interrelated phenomena from the dense core outward to the solar wind that envelops the earth

By Robert Howard

The Deformation of Metals at High Temperatures

The hot-working of metals was long more an art than a science. The study of how metals behave at the level of atoms in crystal lattices is doing much to put the art on a more rational footing

By Hugh J. McQueen and W. J. McGregor Tegart

Departments

50 and 100 Years Ago, April 1975

Science and the Citizen, April 1975

Letters

Letters to the Editors, April 1975

Recommended

Books, April 1975

Mathematical Recreation

Mathematical Games, April 1975

Amateur Scientist

The Amateur Scientist, April 1975

Departments

The Authors, April 1975

Bibliography, April 1975

Purchase To Read More

Digital Issue ?Read or download this issue’s articles online. *A printed copy of this issue is not included. $7.99

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